1. Field of the Invention
The present invention relates to a plasma etching method, a pattern forming method and a cleaning method.
2. Description of the Related Art
A technique is known of finely processing a target film to be etched by a plasma etching by generating plasma from a gas. For example, Japanese Laid-Open Patent Application Publication No. 2005-252186 discloses a technique of depositing a silicon oxide film on a substrate by a thermal oxidation process first, then depositing a high-k (high-dielectric-constant) film on the silicon oxide film by CVD (Chemical Vapor Deposition), and etching the high-k film by using plasma generated from a gas such as Cl2. Also, Japanese Laid-Open Patent Application Publication No. 2004-146787 discloses a technique of etching a high-k film by using plasma generated from a gas such as BCl3.
Moreover, in recent years, an etching technique is demanded that forms deep holes and trenches into a specific target film to be etched, such as a silicon oxide film and an amorphous carbon film, by a plasma etching.
However, when etching selectivity of the target film to be etched, such as the high-k film, to an underlying film cannot be sufficiently obtained, forming the deep and vertical holes and trenches into the target film to be etched becomes difficult, and the etching properties become worse.